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In MySQL there are three main data types: string, numeric, and date and time. SQL Data Types Each column in a database table is required to have a name and a data type. An SQL developer must decide what type of data that will be stored inside each column when creating a table. The data type is a guideline for SQL to understand what type of data is expected inside of each column, and it also identifies how SQL will interact with the stored data. Note: Data types might have different names in different database. And even if the name is the same, the size and other details may be different! Always check the documentation! MySQL Data Types (Version 8.0) In MySQL there are three main data types: string, numeric, and date and time. String data types: Data type Description CHAR(size) A FIXED length string (can contain letters, numbers, and special characters). The size parameter specifies the column length in characters - can be from 0 to 255. Default is 1 VARCHAR(size) A VARIABLE length string (can contain letters, numbers, and special characters). The size parameter specifies the maximum column length in characters - can be from 0 to 65535 BINARY(size) Equal to CHAR(), but stores binary byte strings. The size parameter specifies the column length in bytes. Default is 1 VARBINARY(size) Equal to VARCHAR(), but stores binary byte strings. The size parameter specifies the maximum column length in bytes. TINYBLOB For BLOBs (Binary Large OBjects). Max length: 255 bytes TINYTEXT Holds a string with a maximum length of 255 characters TEXT(size) Holds a string with a maximum length of 65,535 bytes BLOB(size) For BLOBs (Binary Large OBjects). Holds up to 65,535 bytes of data MEDIUMTEXT Holds a string with a maximum length of 16,777,215 characters MEDIUMBLOB For BLOBs (Binary Large OBjects). Holds up to 16,777,215 bytes of data LONGTEXT Holds a string with a maximum length of 4,294,967,295 characters LONGBLOB For BLOBs (Binary Large OBjects). Holds up to 4,294,967,295 bytes of data ENUM(val1, val2, val3, ...) A string object that can have only one value, chosen from a list of possible values. You can list up to 65535 values in an ENUM list. If a value is inserted that is not in the list, a blank value will be inserted. The values are sorted in the order you enter them SET(val1, val2, val3, ...) A string object that can have 0 or more values, chosen from a list of possible values. You can list up to 64 values in a SET list Numeric data types: Data type Description BIT(size) A bit-value type. The number of bits per value is specified in size. The size parameter can hold a value from 1 to 64. The default value for size is 1. TINYINT(size) A very small integer. Signed range is from -128 to 127. Unsigned range is from 0 to 255. The size parameter specifies the maximum display width (which is 255) BOOL Zero is considered as false, nonzero values are considered as true. BOOLEAN Equal to BOOL SMALLINT(size) A small integer. Signed range is from -32768 to 32767. Unsigned range is from 0 to 65535. The size parameter specifies the maximum display width (which is 255) MEDIUMINT(size) A medium integer. Signed range is from -8388608 to 8388607. Unsigned range is from 0 to 16777215. The sizeparameter specifies the maximum display width (which is 255) INT(size) A medium integer. Signed range is from -2147483648 to 2147483647. Unsigned range is from 0 to 4294967295. The size parameter specifies the maximum display width (which is 255) INTEGER(size) Equal to INT(size) BIGINT(size) A large integer. Signed range is from -9223372036854775808 to 9223372036854775807. Unsigned range is from 0 to 18446744073709551615. The size parameter specifies the maximum display width (which is 255) FLOAT(size, d) A floating point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter. This syntax is deprecated in MySQL 8.0.17, and it will be removed in future MySQL versions FLOAT(p) A floating point number. MySQL uses the p value to determine whether to use FLOAT or DOUBLE for the resulting data type. If p is from 0 to 24, the data type becomes FLOAT(). If p is from 25 to 53, the data type becomes DOUBLE() DOUBLE(size, d) A normal-size floating point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter DOUBLE PRECISION(size, d) DECIMAL(size, d) An exact fixed-point number. The total number of digits is specified in size. The number of digits after the decimal point is specified in the d parameter. The maximum number for size is 65. The maximum number for d is 30. The default value for size is 10. The default value for d is 0. DEC(size, d) Equal to DECIMAL(size,d) Note: All the numeric data types may have an extra option: UNSIGNED or ZEROFILL. If you add the UNSIGNED option, MySQL disallows negative values for the column. If you add the ZEROFILL option, MySQL automatically also adds the UNSIGNED attribute to the column. Date and Time data types: Data type Description DATE A date. Format: YYYY-MM-DD. The supported range is from '1000-01-01' to '9999-12-31' DATETIME(fsp) A date and time combination. Format: YYYY-MM-DD hh:mm:ss. The supported range is from '1000-01-01 00:00:00' to '9999-12-31 23:59:59'. Adding DEFAULT and ON UPDATE in the column definition to get automatic initialization and updating to the current date and time TIMESTAMP(fsp) A timestamp. TIMESTAMP values are stored as the number of seconds since the Unix epoch ('1970-01-01 00:00:00' UTC). Format: YYYY-MM-DD hh:mm:ss. The supported range is from '1970-01-01 00:00:01' UTC to '2038-01-09 03:14:07' UTC. Automatic initialization and updating to the current date and time can be specified using DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP in the column definition TIME(fsp) A time. Format: hh:mm:ss. The supported range is from '-838:59:59' to '838:59:59' YEAR A year in four-digit format. Values allowed in four-digit format: 1901 to 2155, and 0000. MySQL 8.0 does not support year in two-digit format. SQL Server Data Types String data types: Data type Description Max size Storage char(n) Fixed width character string 8,000 characters Defined width varchar(n) Variable width character string 8,000 characters 2 bytes + number of chars varchar(max) Variable width character string 1,073,741,824 characters 2 bytes + number of chars text Variable width character string 2GB of text data 4 bytes + number of chars nchar Fixed width Unicode string 4,000 characters Defined width x 2 nvarchar Variable width Unicode string 4,000 characters nvarchar(max) Variable width Unicode string 536,870,912 characters ntext Variable width Unicode string 2GB of text data binary(n) Fixed width binary string 8,000 bytes varbinary Variable width binary string 8,000 bytes varbinary(max) Variable width binary string 2GB image Variable width binary string 2GB Numeric data types: Data type Description Storage bit Integer that can be 0, 1, or NULL tinyint Allows whole numbers from 0 to 255 1 byte smallint Allows whole numbers between -32,768 and 32,767 2 bytes int Allows whole numbers between -2,147,483,648 and 2,147,483,647 4 bytes bigint Allows whole numbers between -9,223,372,036,854,775,808 and 9,223,372,036,854,775,807 8 bytes decimal(p,s) Fixed precision and scale numbers. Allows numbers from -10^38 +1 to 10^38 –1. The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18. The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0 5-17 bytes numeric(p,s) Fixed precision and scale numbers. Allows numbers from -10^38 +1 to 10^38 –1. The p parameter indicates the maximum total number of digits that can be stored (both to the left and to the right of the decimal point). p must be a value from 1 to 38. Default is 18. The s parameter indicates the maximum number of digits stored to the right of the decimal point. s must be a value from 0 to p. Default value is 0 5-17 bytes smallmoney Monetary data from -214,748.3648 to 214,748.3647 4 bytes money Monetary data from -922,337,203,685,477.5808 to 922,337,203,685,477.5807 8 bytes float(n) Floating precision number data from -1.79E + 308 to 1.79E + 308. The n parameter indicates whether the field should hold 4 or 8 bytes. float(24) holds a 4-byte field and float(53) holds an 8-byte field. Default value of n is 53. 4 or 8 bytes real Floating precision number data from -3.40E + 38 to 3.40E + 38 4 bytes Date and Time data types: Data type Description Storage datetime From January 1, 1753 to December 31, 9999 with an accuracy of 3.33 milliseconds 8 bytes datetime2 From January 1, 0001 to December 31, 9999 with an accuracy of 100 nanoseconds 6-8 bytes smalldatetime From January 1, 1900 to June 6, 2079 with an accuracy of 1 minute 4 bytes date Store a date only. From January 1, 0001 to December 31, 9999 3 bytes time Store a time only to an accuracy of 100 nanoseconds 3-5 bytes datetimeoffset The same as datetime2 with the addition of a time zone offset 8-10 bytes timestamp Stores a unique number that gets updated every time a row gets created or modified. The timestamp value is based upon an internal clock and does not correspond to real time. Each table may have only one timestamp variable Other data types: Data type Description sql_variant Stores up to 8,000 bytes of data of various data types, except text, ntext, and timestamp uniqueidentifier Stores a globally unique identifier (GUID) xml Stores XML formatted data. Maximum 2GB cursor Stores a reference to a cursor used for database operations table Stores a result-set for later processing Microsoft Access Data Types Data type Description Storage Text Use for text or combinations of text and numbers. 255 characters maximum Memo Memo is used for larger amounts of text. Stores up to 65,536 characters. Note: You cannot sort a memo field. However, they are searchable Byte Allows whole numbers from 0 to 255 1 byte Integer Allows whole numbers between -32,768 and 32,767 2 bytes Long Allows whole numbers between -2,147,483,648 and 2,147,483,647 4 bytes Single Single precision floating-point. Will handle most decimals 4 bytes Double Double precision floating-point. Will handle most decimals 8 bytes Currency Use for currency. Holds up to 15 digits of whole dollars, plus 4 decimal places. Tip: You can choose which country's currency to use 8 bytes AutoNumber AutoNumber fields automatically give each record its own number, usually starting at 1 4 bytes Date/Time Use for dates and times 8 bytes Yes/No A logical field can be displayed as Yes/No, True/False, or On/Off. In code, use the constants True and False (equivalent to -1 and 0). Note: Null values are not allowed in Yes/No fields 1 bit Ole Object Can store pictures, audio, video, or other BLOBs (Binary Large OBjects) up to 1GB Hyperlink Contain links to other files, including web pages Lookup Wizard Let you type a list of options, which can then be chosen from a drop-down list 4 bytes